Devices powered by an electric power supply generally have a voltage or power range across which they normally may operate safely. These devices may include computers and computer systems, computer components, power supplies, logic boards, hard disk drives and processors. Voltage or power fluctuations in the line connecting the power supply to the device being powered can push voltage or power beyond these normal operating ranges, and risks damaging the equipment.
For example, a computer motherboard is typically designed to be operated at voltages between +12 volts and -12 volts. The computer's power supply is powered from an alternating current (AC) wall outlet, and generates direct current (DC) power to run the computer system. The power supply transmitting the DC operating power may fluctuate, or surge, from time to time, causing the voltage at the power terminal of the component to rise above the +12 V DC limit, or sink below the -12 V DC limit. The safe operating range designed into the motherboard typically takes into account minor surges or dips in power. Therefore, the motherboard may typically operate without any danger to its components even if the operating voltage is pushed slightly beyond its normal operating range. When the operating voltage rises above the upper safe operating limit (an over-voltage condition), or sinks below the lower safe operating limit (an under-voltage condition), the motherboard or components thereof may be damaged or even destroyed by the excess power. Consequently, the end user of the motherboard may spend hundreds of dollars to replace damaged components or even an entire system. A need therefore exists for some method or device that will protect the sensitive internal components of a computer system or other electronic device from these dangerous power surges and dips.
Others have attempted to solve the problems attributable to DC power fluctuations with external surge protectors that plug in to AC wall outlets. The power cord which supplies the AC power to the electronic system is plugged into an external surge protector device, often in the form of a multiple device strip, which protects against AC fluctuations that physically occur outside of the electronic device or system between the wall AC outlet and the system's internal power supply. The general purpose of this approach is to manage the fluctuations at a location closer to the point of origin. The objective of placing the surge protector at this location is to send only safe AC power to the internal power supply, which in turn, should produce only safe DC power. There are several drawbacks to this approach. Most notably, these external surge protectors do not address the problems that arise from power fluctuations occurring inside the system from the power supply unit itself. Although the system is protected from dangerous external AC power fluctuations, there is nothing between the power supply component and the other sensitive electronic components to protect them from fluctuations caused by the power supply. The invention disclosed herein provides protection for electronic components from these types of power fluctuations by managing the flow of power from the internal power source to the internal components of a particular electronic device or system.
Others have attempted to solve the problems attributable to internal power fluctuations with devices that constantly monitor the voltage or power output from a power supply, and then shut down the power supply output when an over-voltage or under-voltage situation is detected. See U.S. Pat. No. 4,951,171 issued on Aug. 21, 1990 to Tran, et al. There are several drawbacks to this approach. First, the Tran invention requires the use of an active circuit to compare the power output level with a reference voltage level, and then determine whether the supply should be shut down. The protection circuit itself must also be powered from some dependent or independent source, because it includes active electronic components. Further, the invention requires numerous, costly components to make up the circuit which is used to monitor the power supply, and to generate the variety of different signals that enable or disable the power supply according to the result of the comparison. Due to the large number of components needed to create the circuit, and their relative complexity, the invention disclosed in Tran is not cost-efficient, and results in an increased cost of manufacture for which the end user ultimately pays. Further, there is no "add-on" circuit which can be installed in units that do not come with the protection circuit factory installed.
Therefore a need exists to provide effective, cost-efficient protection of electronic components from power fluctuations that may occur in an on-board or dedicated power supply.